Heat treating method



United States Patent Ofice 3,433,683 HEAT TREATING METHOD Harry B. Osborn, Jr., Pepper Pike, Ohio, assignor to The Ohio Crankshaft Company, Cleveland, Ohio, a corporation of Ohio No Drawing. iled Jan. 6, 1967, Ser. No. 607,620 U.S. Cl. 14813.2 9 Claims Int. Cl. C21d 1/56; C22f 1/08 ABSTRACT OF THE DISCLOSURE A process of producing heat treated, quenched copper and copper-base alloys having bright, substantially oxide free surfaces by quenching the metal with a quenching medium containing methyl alcohol.

This invention relates to the art of metals heat treating, and more particularly to a method of heat treating copper and copper-base alloys.

The present invention is particularly applicable to use in conjunction with heat treating for grain structure con trol (i.e., annealing) and it will be described with particular reference thereto; however, it will be appreciated that the invention has broader applications and may be used in conjunction with heat treating steps performed for other purposes.

In accordance with the present invention, there is provided in a method of heat treating a material selected from the group consisting of copper and copper-base alloys, including the step of heating the material in air to an elevated temperature at which oxides on the surfaces thereof readily form, the improvement comprising the step of contacting the surfaces when the material is at the surface oxidizing elevated temperature, with a quenching medium containing methyl alcohol in an amount and for a time suflicient to provide a quenched material having surfaces substantially free of oxides.

When copper or copper-base alloys are heated in air to temperatures of about 500 F. or above, surface oxidation takes place rapidly. Most heat treatments for these materials require temperatures well in excess of 500 F. For instance, substantially pure copper is generally annealed at temperatures within the range of about 700- 1200 F. Cartridge brass (containing 30% zinc) is generally annealed at temperatures within the range of about 8001300 F. Cupro-nickel alloy (30% nickel) is generally annealed at temperatures within the range of about 1200l600 F. Thus, surface oxidation is an in herent and undesirable side effect of heat treating copper and copper-base alloys.

In accordance with the prior art practices, the surface oxides formed during heat treatment have been removed by a variety of separate finishing procedures. Some of these have included mechanical removal of the surface oxide as by buffing or polishing; chemical removal of the surface oxide as by pickling with various acids; and electrochemical cleaning. These types of finishing operations are all relatively expensive in that they result in some loss of metal and require the use of expensive chemicals and/ or apparatus.

The present invention obviates these and other disadvantages of the prior art, by providing a heat treating method in which methyl alcohol is added to a quenching medium'which is applied to the copper or copper-base alloy while the material is in its heated condition. While not limiting the invention to any particular theory of operation, it is postulated that the methyl alcohol reduces the oxides formed on the surfaces of the heated material, reconverting the material to its metallic state. Whatever the theory of operation, the present invention provides 3,433,683 Patented Mar. 18, 1969 a heat treated, quenched material having a bright surface substantially free of oxides. Moreover, in accordance with the present invention, none of the material is lost as a result of oxide removal, thus, providing a cost saving. Further, the active material used, methyl alcohol, is readily available and inexpensive, so that the cost of the oxide removal step is nominal. Finally, since most conventional annealing equipment includes quenching means, the present invention may be practiced in such conventional equipment without modification except insofar as it may be necessary to incorporate means for injecting methyl alcohol into the existing quenching means.

In accordance with one limited aspect of the present invention, the heat treating method is practiced by heating the copper or copper-base alloy by induction heating means. This introduces further economies into the process, particularly where copper or copper-base alloy material in the form of continuous strip, is to be heat treated. As compared with fuel fired or resistance heated furnaces, induction furnaces take up less floor space, operate more efficiently, and require less maintenance and upkeep.

Therefore, it is an object of the invention to provide an improved heat treating method.

Another object of the invention is to provide a heat treating method which overcomes certain disadvantages of the prior art.

A further object of the invention is to provide an improved heat treating method for material selected from the group consisting of copper and copper-base alloys, wherein oxides formed on the surfaces of these materials during heating are removed without loss of such materials.

A further object of the invention is to provide a heat treating method wherein the material heat treated is quenched with a quenching medium containing methyl alcohol.

Yet another object of the invention is to provide a heat treating method wherein a material selected from the group consisting of copper and copper-base alloys is induction heated, and then quenched with quenching medium containing methyl alcohol.

Yet another object of the invention is to provide a heat treated, quenched material selected from the group consisting of copper and copper-base alloys, produced in accordance with the method of the present invention.

These and other objects and advantages will become apparent from the following detailed description of the invention including a discussion of the best mode presently contemplated for practicing the invention.

In accordance with the present invention, a material selected from the group consisting of copper and copperbase alloys is fed to a furnace, preferably of the induction type, and heated to a temperature within the range of about 700 to about 1600 F., depending upon the nature of the heat treatment and the composition of the material. As a consequence of heating the material in air, oxides form on the surfaces thereof.

While the material is at the heat treating temperature, the surfaces thereof are contacted with a quenching medium containing methyl alcohol. The amount of methyl alcohol contained in the quenching medium should be an amount suflicient to provide a quenched material having surfaces substantially free of oxides. In one preferred form of the invention, the quenching medium comprises an aqueous solution of methyl alcohol, wherein the alcohol content is within the range of about 1 to about 5 volume percent.

The contacting may be accomplished in any suitable manner, such as spraying the quenching medium On the surfaces thereof, or by immersing the material in a bath of quenching medium. Contact between the surfaces of the material and the quenching medium is maintained until the material is cooled to a temperature below which oxides readily form. Thus, contact should be maintained until the material is at a temperature of 500 F. or below, and preferably 300 F. or below.

The heat treated, quenched material produced in accordance with the present invention, will have bright metallic surfaces, substantially free of oxides.

The present invention has been described in conjunction with certain specific embodiments; however, it is to be appreciated that various changes may be made in the described embodiments without departing from the intended scope and spirit of the present invention.

Having thus described my invention, I claim:

1. In a method of heat treating a material selected from the group consisting of copper and copper-base alloys, including the step of heating said material in air to an elevated temperature at which oxides readily form on the surfaces thereof, the improvement comprising the step of contacting said surfaces when said material is at said elevated temperature, with a quenching medium containing methyl alcohol in an amount and for a time sufficient to provide a quenched material having surfaces substantially free of oxides.

2. The method as defined in claim 1, wherein said contacting step is conducted by spraying said quenching medium on said surfaces of said material.

3. The method as defined in claim 1, wherein said contacting step is conducted by immersing said material in said quenching medium.

4. The method as defined in claim 1, wherein said quenching medium comprises an aqueous solution of methyl alcohol.

5. The method as defined in claim 4, wherein said solution contains from about 1 to about 5 vol. percent methyl alcohol.

6. The method as defined in claim 1, wherein said elevated temperature is attained by induction heating of said material.

7. A method of heat treating a material selected from the group consisting of copper and copper-base alloys comprising the steps of induction heating said material in air to an elevated temperature at least as high as its annealing temperature whereby the surfaces of said material become oxidized, contacting said surfaces when said material is at said elevated temperature, with a quenching medium comprising an aqueous solution containing from about 1 to about 5 vol. percent methyl alcohol, and maintaining contact between said surfaces and said quenching medium until said material is cooled to a temperature below which oxides readily form on said surfaces.

8. The method as defined in claim 7, wherein said contacting step is conducted by immersing said material in said quenching medium.

9. The method as defined in claim 7, wherein said contacting step is conducted by spraying said quenching medium on said surfaces of said material.

References Cited UNITED STATES PATENTS 2,489,529 11/ 1949 Grange 14813.2 2,643,961 6/1953 Snyder et al 14813.2 3,271,207 9/1966 Davis 14828 RICHARD O. DEAN, Primary Examiner.

US. Cl. X.R. 14820.6, 28 

